<template>
<div>
     <router-link
      tag="div"
      to="/"
      class="header-abs"
      v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
  <div class="header-fixed"
  v-show="!showAbs"
  :style="opacityStyle"
  >
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
  </div>
</div>

</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = { opacity }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
      console.log(document.documentElement.scrollTop)
    }
  },
  activated () {
    // 我们应当对某个组件进行绑定而不是对window绑定 不然在任何页面都会onscroll这个事件
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated () {
    // 在离开这个页面的时候会触发这个钩子
    window.removeEventListener('scroll', this.handleScroll)
  }

}
</script>

<style lang="stylus" scoped>
 @import '~styles/variables.styl';
  .header-abs
    position: absolute
    left: .2rem
    top: .2rem
    width: .8rem
    height: .8rem
    line-height: .8rem
    border-radius: .4rem
    text-align: center
    background: rgba(0, 0, 0, .8)
    .header-abs-back
      color: #fff
      font-size: .4rem
  .header-fixed
    z-index: 2
    position: fixed
    top: 0
    left: 0
    right: 0
    height: $headerHeight
    line-height: $headerHeight
    text-align: center
    color: #fff
    background: $bgColor
    font-size: .32rem
    .header-fixed-back
      position: absolute
      top: 0
      left: 0
      width: .64rem
      text-align: center
      font-size: .4rem
      color: #fff
</style>
